motors and compressed air presentation

motors and compressed air presentation - Motors and...

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Unformatted text preview: Motors and Compressed Air MAE 406 Energy Conservation in Industry Stephen Terry Electric Motors In use throughout every manufacturing plant, office, and home Consume 64% of all electricity generated. About 1 billion motors in service today consuming over 2 trillion kWh of energy per year. Types of Motors Direct Current (DC) Used in small applications and where precise speed is required. Also used in very large applications (>1,000 hp) Synchronous Motors Used for precise speed control and large, slow speed applications Induction Motors Most common type used in industry Induction Motor Fundamentals A voltage is applied to the stator causing a rotating magnetic field This induces a counter EMF in the rotor by the flux of magnetic fields A rotating field is developed in the windings and the rotor tries to follow the magnetic field in the stator The rotor cannot spin as fast as the stator because of the load and the motor slips some. An 1,800 rpm motor has a shaft speed of between 1,700 and 1,760 rpm, depending on load. Motor Fundamentals Induction motors have different designs based on application. Speed vs. torque Motors require large power at startup (lock rotor Amps, LRA) briefly, then operate at running load amps (RLA). National Electrical Manufacturers Association (NEMA) sets standards. Motor Power Motor size in US is measured in horsepower (hp) output. 1 hp = 746 Watts = 2,545 BTU/hr Motors convert electric power to shaft power Efficiency is a measure of the conversion rate. Efficiency ranges between 50% and 96% for most motors. Energy loss is in the form of heat High Efficiency Motors A few years ago, all motors manufactured will meet minimum efficiency requirements. Many old motors are still in service Efficiency improvements are due to improved magnets, better heat dissipation, better windings, and lower friction bearings Rewound motors Rewinding motors requires that the windings be removed by heating....
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This note was uploaded on 08/01/2008 for the course MAE 406 taught by Professor Eckerlin,terry during the Fall '07 term at N.C. State.

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motors and compressed air presentation - Motors and...

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